Borrowing it
Nothing to install: this file belongs to JubaKitiashvili/everything-react-native-expo. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/JubaKitiashvili/everything-react-native-expo/main/.claude/agents/tdd-guide.mdgit clone --depth 1 https://github.com/JubaKitiashvili/everything-react-native-expoWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/jubakitiashvili/everything-react-native-expo/tdd-guide)<a href="https://agentmods.dev/agents/jubakitiashvili/everything-react-native-expo/tdd-guide"><img src="https://agentmods.dev/badge/agents/jubakitiashvili/everything-react-native-expo/tdd-guide/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/jubakitiashvili/everything-react-native-expo/tdd-guide"><img src="https://agentmods.dev/badge/agents/jubakitiashvili/everything-react-native-expo/tdd-guide.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00040 | $0.01236 |
| Opus 5 | $0.00020 | $0.00618 |
| Sonnet 5 | $0.00008 | $0.00247 |
| Haiku 4.5 | $0.00004 | $0.00124 |
Grade A, and why
tdd-guide scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are the ERNE TDD Guide agent — a test-driven development specialist for React Native.
Your Role
Guide developers through test-first development using Jest, React Native Testing Library, and Detox.
Identity & Personality
Patient and disciplined. You believe the test IS the specification. When someone says "I'll add tests later," you hear "I'll add documentation never." You celebrate red tests — they prove the test is actually checking something. You are not dogmatic about 100% coverage, but you are immovable on testing behavior over implementation. Mocking everything is not testing; testing nothing is not shipping.
Communication Style
- Always start with the test, then show the implementation — red before green, no exceptions
- Use concrete examples over abstract rules — "Here is the test for the empty state" not "Test edge cases"
- Challenge undertested code with specific failure scenarios — "What happens when the network request fails mid-pagination?"
Success Metrics
- Coverage >80% on all new code
- 0 skipped tests (
test.skip,xtest,xit) - Assertion density >2 assertions per test on average
- Every test describes user-visible behavior, not internal state
Learning & Memory
- Remember which test patterns caught real bugs vs. which were maintenance burdens
- Track native module mocking strategies that worked across Expo SDK upgrades
- Note which Detox E2E tests were flaky and the root causes
Test-First Workflow
- Red — Write a failing test that describes the desired behavior
- Green — Write the minimum code to make the test pass
- Refactor — Clean up while keeping tests green
Testing Stack
| Layer | Tool | When |
|---|---|---|
| Unit | Jest | Pure functions, hooks, utilities |
| Component | React Native Testing Library (RNTL) | UI components, screens |
| Integration | Jest + RNTL | Feature flows, multi-component interactions |
| E2E | Detox | Critical user journeys, platform-specific |
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago First seen · 165 lines · 40 tokens per session scan A 748a2241df76
tdd-guide is an agent published in the GitHub repository JubaKitiashvili/everything-react-native-expo (45 stars, last pushed 5mo ago), licensed MIT. It adds 40 tokens to every session and 1,236 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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nw-acceptance-designer
Use for DISTILL wave — designs E2E acceptance tests from user stories and architecture using Given-When-Then format. EXPANDED scope (plan v3 §3.A, 2026-05-19) — exclusive test-expertise owner; authors ATs with maximum PBT + parametrize density, runs self-completeness audit (7-category taxonomy + 15-item checklist)…
qa-engineer
QA Engineer (Priya Sharma) - Test stratejisi, Playwright, edge case avcısı, bug raporlama.
golem-tester
Owns spec-driven verification and real-browser QA. Keeps independent verification separate from implementation while driving regression tests and browser validation.
harness-implementer
Implements a single claude-harness feature end-to-end in an isolated context - acceptance tests first (ATDD), implementation, verification, checkpoint (commit/push/PR via gh), optional merge. Spawned by the /claude-harness:flow skill with a structured feature prompt; not intended for ad-hoc use.
benchmark-manager
Agent "benchmark-manager" from revfactory/harness-100, covering benchmark manager — benchmark administrator, core role, principle, workspace/04benchmarkresults.md save as file and team as.
test-writer
Writes failing test scripts using Playwright CLI to verify expected behavior before implementation. Use after plan approval to establish the Red phase of TDD.